Tailoring the Thermodynamics and Kinetics of Mg–Li Alloy for a MgH₂‐Based Anode for Lithium‐Ion Batteries

Abstract

Understanding the lithiation–delithiation of the Mg–Li alloy during the absorption–desorption of hydrogen is essential for the development of Li‐ion batteries with MgH2 as a negative electrode. Tuning the hydrogenation–dehydrogenation kinetics and thermodynamics of the Mg–Li alloy could also be helpful to develop a lightweight material for on‐board hydrogen‐storage applications. Single‐phase Li3Mg7 (the highest % of lithium compound) was prepared by ball milling of LiH and MgH2 as precursors of Li and Mg followed by dehydrogenation at 400 °C under dynamic vacuum conditions. The cyclic hydrogenation–dehydrogenation behavior of the intermetallic was studied in detail. During hydrogenation, Li3Mg7 was delithiated to LiH and MgH2, whereas during dehydrogenation, LiH and MgH2 were lithiated to form the Li3Mg7 phase along with a Mg–Li solid solution. The hydrogenation–dehydrogenation kinetics of pristine Li3Mg7 were found to be slow. The hydrogenation–dehydrogenation kinetics were remarkably improved by doping with ZrCl4 as a catalyst. The activation energy and the thermodynamic parameters of the uncatalyzed and catalyzed alloy were evaluated, and the results were compared.

Understanding Capacity Fading of MgH2 Conversion-Type Anodes via Structural Morphology Changes and Electrochemical Impedance

“…However, its application as an anode is still a challenge owing to capacity fading after several cycles . MgH 2 can interact with 2Li by undergoing a conversion reaction, leading to the formation of 2LiH and Mg. At low cycling rate (C/100), MgH 2 can exchange up to 2.9 Li equiv during the first discharge with two plateaus at 0.44 V (Δ x ≈ 1.8Li) and 0.095 V, the latter step being attributed to the formation of the hcp Mg-rich and bcc Li-rich Mg–Li solid solutions. , The delithiation of the Li 3 Mg 7 phase has been found to be reversible under hydrogen pressure (2 MPa) at high temperatures (200 °C), which may be of interest for LIB MgH 2 -based anodes . However, the formation of these solid solutions can be avoided by restraining the discharge by capacity limit or voltage cutoff.…”

“…8,16 The delithiation of the Li3Mg7 phase has been found to be reversible under hydrogen pressure (2 MPa) at high temperatures (200°C), which may be of interest for LIB MgH2-based anodes. 18 However, the formation of these solid solutions can be avoided by restraining the discharge by capacity limit or voltage cut-off. The poor electric conductivity of MgH2 has to be considered.…”

Study on Influencing Factors of Consistency in Manufacturing Process of Vehicle Lithium‐Ion Battery Based on Correlation Coefficient and Multivariate Linear Regression Model

“…In the research of cell consistency, literature [8] proposes that actual capacity, internal resistance, and self-discharge rate are the key indicators to judge cell consistency. Literature [9] discusses the cell consistency researches for electric vehicles, and studies the thermodynamic and kinetic factors affecting consistency by impedance spectroscopy method, and establishes correlation with electrode design parameters. Literature [10] studies the influence of battery manufacturing process on consistency, focusing on optimizing battery sorting by using characteristic parameters of volume distribution curve, and analyzing the causes of battery inconsistency through the comparison of cycle life.…”